Aspects of the disclosure relate to networked computing technologies and location services. In particular, aspects of the disclosure relate to systems, methods, apparatus, and computer readable media for using wireless local area network (WLAN) access points (APs), Secure User Plane Location (SUPL), Long Term Evolution (LTE) positioning protocol (LPP), and/or LPP Extensions (LPPe) to determine the location of a mobile device such as a cellphone, smartphone or laptop.
A WLAN AP may be an AP supporting any of the IEEE 802.11 protocols and may then be referred to as a WiFi AP. A WLAN AP may also or instead support Bluetooth (BT) or some other short range communications technology. A number of methods exist whereby the location of a mobile device nearby to one or more WLAN APs may be obtained. One set of methods which may be designated “mobile centric” are supported by the Secure User Plane Location (SUPL) solution defined by the Open Mobile Alliance (OMA). With this solution, a mobile device detects the identities (IDs) for, and possibly makes measurements of radio signals from, one or more nearby WLAN APs. The detected WLAN AP IDs and optionally the WLAN AP signal measurements are then combined with known locations for the WLAN APs to compute a location estimate for the mobile device either by the mobile device itself or in a SUPL Location Platform (SLP) if the detected WLAN AP IDs and any measurements are transferred by the mobile device to the SLP. With an alternative method (e.g. defined in IEEE 802.11 standards for WiFi APs) which may be designated as “network centric”, WLAN APs detect signals from a mobile device and may make measurements of the signals and then compute a location estimate for the mobile device or transfer the measurements to a separate location server to perform the location computation.
Limitations applicable to mobile centric methods such as SUPL may include an inability of a mobile device to make useful measurements of signals received from WLAN APs (e.g. measurements of round trip signal propagation time (RTT)) if such measurements require certain actions from WLAN APs (e.g. as defined in IEEE 802.11 standards) and these actions are not supported by WLAN APs or not provided by WLAN APs to a particular mobile device. Further limitations may include reliance on measurements made just by the mobile device which may be less accurate (and less reliable) than measurements made by WLAN APs which may be at several different locations and may be considered more trustworthy by a network operator. In addition, a mobile device may measure signals from WLAN APs that lie predominantly in one direction as seen from the mobile device due to stronger signal reception from this direction (e.g. such as when a mobile device measures signals from WLAN APs that are in or near to a corridor in a building when the mobile device is at one end of the corridor). As is known in the art, using measurements such as signal strength, RTT or Time Difference Of Arrival (TDOA) for signals coming from approximately the same direction may significantly magnify measurement errors due to poor geometry resulting in a less accurate location estimate compared to the case where a mobile device measures WLAN AP signals from several or many different directions.
Limitations applicable to network centric methods such as those defined for a WiFi AP by IEEE 802.11 standards may include an unwillingness by a mobile device to participate (to the extent demanded by any method) if the mobile device is unwilling to be located for the benefit of some unknown (and thus not trusted) external client. A further limitation may be an inability of a WLAN AP or some location server controlling a WLAN AP to associate a known global identity for a mobile device with an identity or address used for WLAN signaling. For example, with IEEE 802.11 signaling, a mobile device would normally be identified by a 48 bit Media Access Control (MAC) address whereas the same mobile device may be identified for cellular communications using an International Mobile Subscriber Identity (IMSI) containing up to 15 decimal digits or an International Mobile Equipment Identity (IMEI) containing 15 decimal digits. Any location obtained for a mobile device may then be associated with the mobile device MAC address but not with the mobile device IMSI or IMEI in which case the location may not be available to a client that requests the mobile device location using the IMSI or IMEI. A yet further limitation may be that a mobile device does not receive or ignores location requests from nearby WLAN APs and/or that WLAN APs remote from a mobile device are mistakenly requested by a location server to locate the mobile device.
Due to the limitations of existing mobile centric and network centric location methods associated with locating a mobile device nearby to one or more WLAN APs, there may be an advantage in other methods of locating a mobile device in such scenarios.